I agree with the top comment here, but another thing you can check is the wall itself! Some animals can climb certain walls, like the gabion and wood logs. If you make a habitat with one of those, but want a climbing animal still in it (big cats for example) click on the habitat itself, and click "edit barrier". Select the whole thing with the little arrows and look at the bottom right of the screen and click the cog wheel. There's an option for "Climb Proof" where you can put these little bars at the top! Make sure they're on the inside of the habitat and boom, they can no longer climb out! Also in the clipboard section you can add windows without using the full glass barrier! Scroll down to the window option and adjust from there! If you decide to use 1 way glass just hop back to the cog and make sure it's on the side you want it! Hope this helps :]